Many useful oil-based agricultural chemicals are less effective than desired because they do not spread well. It is typical to apply oil-based chemicals using a carrier such as animal, vegetable, or paraffin oils or to apply dormant oils as aqueous sprays. The bulk surface tension of a liquid plays a key role in its ability to spread on hydrophobic surfaces such as the waxy cuticle of a leaf or the exoskeleton of an arthropod. If the surface tension of a liquid is not sufficiently low, the droplet will not spread effectively. Thus, there is a need for adjuvants which reduce the surface tension of lipophilic liquids and, thereby, increase the effectiveness of oil-based agricultural chemicals.
The use of oils as adjuvants or carriers for agricultural applications is well known. Paraffinic, animal and vegetable oils have been used in formulations for dormant spray oils, in preparations for the management of insects and mites including oils that suffocate arthropod pests by clogging their spiracles, in crop oil concentrates and crop oils, and in emulsifiable concentrates. One of the effects of the oil is to increase the penetration of pesticides into the target organism. In addition, the oils often enhance spreading on target surfaces, which increases the effectiveness of the pesticide being applied.
According to P. J. McCall, et al. (J. Agric. Food Chem., 34(2), 235-8), the addition of a crop oil concentrate (COC) to atrazine spray solutions significantly increased the amount of pesticide absorbed by giant foxtail sprayed with the chemical. Typically, 30% of the applied chemical penetrated the leaf in the presence of COC, while only 10% penetrated without COC. Kulkarni, et al (U.S. Pat. No. 4,514,319) disclosed relatively high molecular weight lipophilically modified silicones that, when used in connection with organosilicone surfactants, reduced the surface tension of hydrocarbon oils containing hydrophobic fillers, thus providing high efficiency antifoam compositions. EP 648413 A, to Murphy, et a., discloses the use of alkyltrisiloxanes as spreading agents for agricultural oils.
U.S. Pat. No. 4,171,267 to McAfee, et al, disclosed an organopolysiloxane fluid as a component of a miscible composition for lubricating organic fibers that contained a hydrocarbon oil and a bridging agent obtained by reacting an organopolysiloxane with a long chain alcohol.
Fluoroalkyl-substituted polysiloxanes are also known in the art, and have been used to modify the surface characteristics of a substrate, usually providing water and/or oil repellency or lubrication.
For example, JP 07-053719 illustrates a process for preparing fluoroalkylpolysiloxanes by hydrosilation with a corresponding polysiloxane containing MeSi(H)O.sub.2/2 units. Yamamoto, et al., (U.S. Pat. No. 4,968,828) demonstrate the preparation of disiloxanes containing both terminal fluoroalkyl and SiH moieties, useful as a modifier for improving the surface properties of various materials. Saho, etal., (U.S. Pat. No. 5,047,449) demonstrate a process for the preparation of polysiloxanes endcapped with fluoroalkyl and polyether substituents. O'Lenick (U.S. Pat. No. 5,446,114) demonstrates the synthesis of fluorinated dimethicone copolyols which pass water and air but not oil when applied to textiles.